1
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Zappa S, Berne C, Morton Iii RI, Whitfield GB, De Stercke J, Brun YV. The HmrABCX pathway regulates the transition between motile and sessile lifestyles in Caulobacter crescentus by a mechanism independent of hfiA transcription. mBio 2024:e0100224. [PMID: 39230277 DOI: 10.1128/mbio.01002-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Accepted: 06/03/2024] [Indexed: 09/05/2024] Open
Abstract
During its cell cycle, the bacterium Caulobacter crescentus switches from a motile, free-living state, to a sessile surface-attached cell. During this coordinated process, cells undergo irreversible morphological changes, such as shedding of their polar flagellum and synthesis of an adhesive holdfast at the same pole. In this work, we used genetic screens to identify genes involved in the regulation of the transition from the motile to the sessile lifestyle. We identified a predicted hybrid histidine kinase that inhibits biofilm formation and promotes the motile lifestyle: HmrA (holdfast and motility regulator A). Genetic screens and genomic localization led to the identification of additional genes that form a putative phosphorelay pathway with HmrA. We postulate that the Hmr pathway acts as a rheostat to control the proportion of cells harboring a flagellum or a holdfast in the population. Further genetic analysis suggests that the Hmr pathway impacts c-di-GMP synthesis through the diguanylate cyclase DgcB pathway. Our results also indicate that the Hmr pathway is involved in the regulation of motile to sessile lifestyle transition as a function of various environmental factors: biofilm formation is repressed when excess copper is present and derepressed under non-optimal temperatures. Finally, we provide evidence that the Hmr pathway regulates motility and adhesion without modulating the transcription of the holdfast synthesis regulator HfiA. IMPORTANCE Complex communities attached to a surface, or biofilms, represent the major lifestyle of bacteria in the environment. Such a sessile state enables the inhabitants to be more resistant to adverse environmental conditions. Thus, having a deeper understanding of the underlying mechanisms that regulate the transition between the motile and the sessile states could help design strategies to improve biofilms when they are beneficial or impede them when they are detrimental. For Caulobacter crescentus motile cells, the transition to the sessile lifestyle is irreversible, and this decision is regulated at several levels. In this work, we describe a putative phosphorelay that promotes the motile lifestyle and inhibits biofilm formation, providing new insights into the control of adhesin production that leads to the formation of biofilms.
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Affiliation(s)
- Sébastien Zappa
- Département de microbiologie, infectiologie et immunologie, Université de Montréal, Montréal, Quebec, Canada
| | - Cécile Berne
- Département de microbiologie, infectiologie et immunologie, Université de Montréal, Montréal, Quebec, Canada
| | | | - Gregory B Whitfield
- Département de microbiologie, infectiologie et immunologie, Université de Montréal, Montréal, Quebec, Canada
| | - Jonathan De Stercke
- Département de microbiologie, infectiologie et immunologie, Université de Montréal, Montréal, Quebec, Canada
| | - Yves V Brun
- Département de microbiologie, infectiologie et immunologie, Université de Montréal, Montréal, Quebec, Canada
- Department of Biology, Indiana University, Bloomington, Indiana, USA
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2
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O'Hara MT, Shimozono TM, Dye KJ, Harris D, Yang Z. Surface hydrophilicity promotes bacterial twitching motility. mSphere 2024:e0039024. [PMID: 39194233 DOI: 10.1128/msphere.00390-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2024] [Accepted: 06/24/2024] [Indexed: 08/29/2024] Open
Abstract
Twitching motility is a form of bacterial surface translocation powered by the type IV pilus (T4P). It is frequently analyzed by interstitial colony expansion between agar and the polystyrene surfaces of petri dishes. In such assays, the twitching motility of Acinetobacter nosocomialis was observed with MacConkey but not Luria-Bertani (LB) agar media. One difference between these two media is the presence of bile salts as a selective agent in MacConkey but not in LB. Here, we demonstrate that the addition of bile salts to LB allowed A. nosocomialis to display twitching. Similarly, bile salts enhanced the twitching of Acinetobacter baumannii and Pseudomonas aeruginosa in LB. These observations suggest that there is a common mechanism, whereby bile salts enhance bacterial twitching and promote interstitial colony expansion. Bile salts disrupt lipid membranes and apply envelope stress as detergents. Surprisingly, their stimulatory effect on twitching appears not to be related to a bacterial physiological response to stressors. Rather, it is due to their ability to alter the physicochemical properties of a twitching surface. We observed that while other detergents promoted twitching like bile salts, stresses applied by antibiotics, including the outer membrane-targeting polymyxin B, did not enhance twitching motility. More importantly, bacteria displayed increased twitching on hydrophilic surfaces such as those of glass and tissue culture-treated polystyrene plastics, and bile salts no longer stimulated twitching on these surfaces. Together, our results show that altering the hydrophilicity of a twitching surface significantly impacts T4P functionality. IMPORTANCE The bacterial type IV pilus (T4P) is a critical virulence factor for many medically important pathogens, some of which are prioritized by the World Health Organization for their high levels of antibiotic resistance. The T4P is known to propel bacterial twitching motility, the analysis of which provides a convenient assay for T4P functionality. Here, we show that bile salts and other detergents augment the twitching of multiple bacterial pathogens. We identified the underlying mechanism as the alteration of surface hydrophilicity by detergents. Consequently, hydrophilic surfaces like those of glass or plasma-treated polystyrene promote bacterial twitching, bypassing the requirement for detergents. The implication is that surface properties, such as those of tissues and medical implants, significantly impact the functionality of bacterial T4P as a virulence determinant. This offers valuable insights for developing countermeasures against the colonization and infection by bacterial pathogens of critical importance to human health on a global scale.
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Affiliation(s)
- Megan T O'Hara
- Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA
| | - Tori M Shimozono
- Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA
| | - Keane J Dye
- Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA
| | - David Harris
- Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA
| | - Zhaomin Yang
- Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA
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3
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Tekedar HC, Patel F, Blom J, Griffin MJ, Waldbieser GC, Kumru S, Abdelhamed H, Dharan V, Hanson LA, Lawrence ML. Tad pili contribute to the virulence and biofilm formation of virulent Aeromonas hydrophila. Front Cell Infect Microbiol 2024; 14:1425624. [PMID: 39145307 PMCID: PMC11322086 DOI: 10.3389/fcimb.2024.1425624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Accepted: 07/01/2024] [Indexed: 08/16/2024] Open
Abstract
Type IV pili (T4P) are versatile proteinaceous protrusions that mediate diverse bacterial processes, including adhesion, motility, and biofilm formation. Aeromonas hydrophila, a Gram-negative facultative anaerobe, causes disease in a wide range of hosts. Previously, we reported the presence of a unique Type IV class C pilus, known as tight adherence (Tad), in virulent Aeromonas hydrophila (vAh). In the present study, we sought to functionalize the role of Tad pili in the pathogenicity of A. hydrophila ML09-119. Through a comprehensive comparative genomics analysis of 170 A. hydrophila genomes, the conserved presence of the Tad operon in vAh isolates was confirmed, suggesting its potential contribution to pathogenicity. Herein, the entire Tad operon was knocked out from A. hydrophila ML09-119 to elucidate its specific role in A. hydrophila virulence. The absence of the Tad operon did not affect growth kinetics but significantly reduced virulence in catfish fingerlings, highlighting the essential role of the Tad operon during infection. Biofilm formation of A. hydrophila ML09-119 was significantly decreased in the Tad operon deletant. Absence of the Tad operon had no effect on sensitivity to other environmental stressors, including hydrogen peroxide, osmolarity, alkalinity, and temperature; however, it was more sensitive to low pH conditions. Scanning electron microscopy revealed that the Tad mutant had a rougher surface structure during log phase growth than the wildtype strain, indicating the absence of Tad impacts the outer surface of vAh during cell division, of which the biological consequences are unknown. These findings highlight the role of Tad in vAh pathogenesis and biofilm formation, signifying the importance of T4P in bacterial infections.
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Affiliation(s)
- Hasan C. Tekedar
- College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States
| | - Fenny Patel
- College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States
| | - Jochen Blom
- Bioinformatics & Systems Biology, Justus-Liebig-University Giessen, Giessen, Germany
| | - Matt J. Griffin
- College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States
- Thad Cochran National Warmwater Aquaculture Center, Stoneville, MS, United States
| | | | - Salih Kumru
- Faculty of Fisheries, Recep Tayyip Erdogan University, Rize, Türkiye
| | - Hossam Abdelhamed
- College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States
| | - Vandana Dharan
- College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States
| | - Larry A. Hanson
- College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States
| | - Mark L. Lawrence
- College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States
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4
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Whitfield GB, Brun YV. The type IVc pilus: just a Tad different. Curr Opin Microbiol 2024; 79:102468. [PMID: 38579360 DOI: 10.1016/j.mib.2024.102468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 03/12/2024] [Accepted: 03/14/2024] [Indexed: 04/07/2024]
Abstract
Bacteria utilize type IV pili (T4P) to interact with their environment, where they facilitate processes including motility, adherence, and DNA uptake. T4P require multisubunit, membrane-spanning nanomachines for assembly. The tight adherence (Tad) pili are an Archaea-derived T4P subgroup whose machinery exhibits significant mechanistic and architectural differences from bacterial type IVa and IVb pili. Most Tad biosynthetic genes are encoded in a single locus that is widespread in bacteria due to facile acquisition via horizontal gene transfer. These loci experience extensive structural rearrangements, including the acquisition of novel regulatory or biosynthetic genes, which fine-tune their function. This has permitted their integration into many different bacterial lifestyles, including the Caulobacter crescentus cell cycle, Myxococcus xanthus predation, and numerous plant and mammalian pathogens and symbionts.
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Affiliation(s)
- Gregory B Whitfield
- Département de Microbiologie, Infectiologie, et Immunologie, Université de Montréal, C.P. 6128, succ. Centre-ville, Montréal, Québec H3C 3J7, Canada.
| | - Yves V Brun
- Département de Microbiologie, Infectiologie, et Immunologie, Université de Montréal, C.P. 6128, succ. Centre-ville, Montréal, Québec H3C 3J7, Canada
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5
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Wang Y, Theodore M, Xing Z, Narsaria U, Yu Z, Zeng L, Zhang J. Structural mechanisms of Tad pilus assembly and its interaction with an RNA virus. SCIENCE ADVANCES 2024; 10:eadl4450. [PMID: 38701202 PMCID: PMC11067988 DOI: 10.1126/sciadv.adl4450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 04/03/2024] [Indexed: 05/05/2024]
Abstract
Caulobacter crescentus Tad (tight adherence) pili, part of the type IV pili family, are crucial for mechanosensing, surface adherence, bacteriophage (phage) adsorption, and cell-cycle regulation. Unlike other type IV pilins, Tad pilins lack the typical globular β sheet domain responsible for pilus assembly and phage binding. The mechanisms of Tad pilus assembly and its interaction with phage ΦCb5 have been elusive. Using cryo-electron microscopy, we unveiled the Tad pilus assembly mechanism, featuring a unique network of hydrogen bonds at its core. We then identified the Tad pilus binding to the ΦCb5 maturation protein (Mat) through its β region. Notably, the amino terminus of ΦCb5 Mat is exposed outside the capsid and phage/pilus interface, enabling the attachment of fluorescent and affinity tags. These engineered ΦCb5 virions can be efficiently assembled and purified in Escherichia coli, maintaining infectivity against C. crescentus, which presents promising applications, including RNA delivery and phage display.
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Affiliation(s)
- Yuhang Wang
- Center for Phage Technology, Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Matthew Theodore
- Center for Phage Technology, Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Zhongliang Xing
- Center for Phage Technology, Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Utkarsh Narsaria
- Center for Phage Technology, Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - Zihao Yu
- Center for Phage Technology, Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
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6
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Hellenbrand CN, Stevenson DM, Gromek KA, Amador-Noguez D, Hershey DM. A deoxynucleoside triphosphate triphosphohydrolase promotes cell cycle progression in Caulobacter crescentus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.25.591158. [PMID: 38712277 PMCID: PMC11071499 DOI: 10.1101/2024.04.25.591158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Intracellular pools of deoxynucleoside triphosphates (dNTPs) are strictly maintained throughout the cell cycle to ensure accurate and efficient DNA replication. DNA synthesis requires an abundance of dNTPs, but elevated dNTP concentrations in nonreplicating cells delay entry into S phase. Enzymes known as deoxyguanosine triphosphate triphosphohydrolases (Dgts) hydrolyze dNTPs into deoxynucleosides and triphosphates, and we propose that Dgts restrict dNTP concentrations to promote the G1 to S phase transition. We characterized a Dgt from the bacterium Caulobacter crescentus termed flagellar signaling suppressor C (fssC) to clarify the role of Dgts in cell cycle regulation. Deleting fssC increases dNTP levels and extends the G1 phase of the cell cycle. We determined that the segregation and duplication of the origin of replication (oriC) is delayed in ΔfssC, but the rate of replication elongation is unchanged. We conclude that dNTP hydrolysis by FssC promotes the initiation of DNA replication through a novel nucleotide signaling pathway. This work further establishes Dgts as important regulators of the G1 to S phase transition, and the high conservation of Dgts across all domains of life implies that Dgt-dependent cell cycle control may be widespread in both prokaryotic and eukaryotic organisms.
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Affiliation(s)
| | - David M. Stevenson
- Department of Bacteriology, University of Wisconsin – Madison, Madison, WI 53706, USA
| | - Katarzyna A. Gromek
- Department of Bacteriology, University of Wisconsin – Madison, Madison, WI 53706, USA
| | - Daniel Amador-Noguez
- Department of Bacteriology, University of Wisconsin – Madison, Madison, WI 53706, USA
| | - David M. Hershey
- Department of Bacteriology, University of Wisconsin – Madison, Madison, WI 53706, USA
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7
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Medici IF, Bartrolí L, Guaimas FF, Fulgenzi FR, Molina CL, Sánchez IE, Comerci DJ, Mongiardini E, Soler-Bistué A. The distinct cell physiology of Bradyrhizobium at the population and cellular level. BMC Microbiol 2024; 24:129. [PMID: 38643099 PMCID: PMC11031950 DOI: 10.1186/s12866-024-03272-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 03/22/2024] [Indexed: 04/22/2024] Open
Abstract
The α-Proteobacteria belonging to Bradyrhizobium genus are microorganisms of extreme slow growth. Despite their extended use as inoculants in soybean production, their physiology remains poorly characterized. In this work, we produced quantitative data on four different isolates: B. diazoefficens USDA110, B. diazoefficiens USDA122, B. japonicum E109 and B. japonicum USDA6 which are representative of specific genomic profiles. Notably, we found conserved physiological traits conserved in all the studied isolates: (i) the lag and initial exponential growth phases display cell aggregation; (ii) the increase in specific nutrient concentration such as yeast extract and gluconate hinders growth; (iii) cell size does not correlate with culture age; and (iv) cell cycle presents polar growth. Meanwhile, fitness, cell size and in vitro growth widely vary across isolates correlating to ribosomal RNA operon number. In summary, this study provides novel empirical data that enriches the comprehension of the Bradyrhizobium (slow) growth dynamics and cell cycle.
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Affiliation(s)
- Ian F Medici
- Instituto de Investigaciones Biotecnológicas, IIB-IIBIO, Universidad Nacional de San Martín- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. 25 de Mayo y Francia CP (1650), San Martín, Prov. de Buenos Aires, Argentina
| | - Leila Bartrolí
- Instituto de Investigaciones Biotecnológicas, IIB-IIBIO, Universidad Nacional de San Martín- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. 25 de Mayo y Francia CP (1650), San Martín, Prov. de Buenos Aires, Argentina
| | - Francisco F Guaimas
- Instituto de Investigaciones Biotecnológicas, IIB-IIBIO, Universidad Nacional de San Martín- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. 25 de Mayo y Francia CP (1650), San Martín, Prov. de Buenos Aires, Argentina
| | - Fabiana R Fulgenzi
- Instituto de Investigaciones Biotecnológicas, IIB-IIBIO, Universidad Nacional de San Martín- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. 25 de Mayo y Francia CP (1650), San Martín, Prov. de Buenos Aires, Argentina
| | - Charo Luciana Molina
- Instituto de Investigaciones Biotecnológicas, IIB-IIBIO, Universidad Nacional de San Martín- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. 25 de Mayo y Francia CP (1650), San Martín, Prov. de Buenos Aires, Argentina
| | - Ignacio Enrique Sánchez
- Laboratorio de Fisiología de Proteínas, Facultad de Ciencias Exactas y Naturales, CONICET Instituto de Química Biológica, Facultad de Ciencias Exactas y Naturales (IQUIBICEN), Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Diego J Comerci
- Instituto de Investigaciones Biotecnológicas, IIB-IIBIO, Universidad Nacional de San Martín- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. 25 de Mayo y Francia CP (1650), San Martín, Prov. de Buenos Aires, Argentina
| | - Elías Mongiardini
- Instituto de Biotecnología y Biología Molecular (IBBM), Facultad de Ciencias Exactas, UNLP y CCT-La Plata-CONICET, La Plata, Argentina
| | - Alfonso Soler-Bistué
- Instituto de Investigaciones Biotecnológicas, IIB-IIBIO, Universidad Nacional de San Martín- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. 25 de Mayo y Francia CP (1650), San Martín, Prov. de Buenos Aires, Argentina.
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8
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Chong TN, Panjalingam M, Saurabh S, Shapiro L. Phosphatase to kinase switch of a critical enzyme contributes to timing of cell differentiation. mBio 2024; 15:e0212523. [PMID: 38055339 PMCID: PMC10790692 DOI: 10.1128/mbio.02125-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 10/20/2023] [Indexed: 12/08/2023] Open
Abstract
IMPORTANCE The process of cell differentiation is highly regulated in both prokaryotic and eukaryotic organisms. The aquatic bacterium, Caulobacter crescentus, undergoes programmed cell differentiation from a motile swarmer cell to a stationary stalked cell with each cell cycle. This critical event is regulated at multiple levels. Kinase activity of the bifunctional enzyme, PleC, is limited to a brief period when it initiates the molecular signaling cascade that results in cell differentiation. Conversely, PleC phosphatase activity is required for pili formation and flagellar rotation. We show that PleC is localized to the flagellar pole by the scaffold protein, PodJ, which is known to suppress PleC kinase activity in vitro. PleC mutants that are unable to bind PodJ have increased kinase activity in vivo, resulting in premature differentiation. We propose a model in which PodJ regulation of PleC's enzymatic activity contributes to the robust timing of cell differentiation during the Caulobacter cell cycle.
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Affiliation(s)
- Trisha N. Chong
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, California, USA
| | - Mayura Panjalingam
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, California, USA
| | - Saumya Saurabh
- Department of Chemistry, New York University, New York, New York, USA
| | - Lucy Shapiro
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, California, USA
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9
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Zappa S, Berne C, Morton RI, De Stercke J, Brun YV. The HmrABCX pathway regulates the transition between motile and sessile lifestyles in Caulobacter crescentus by a HfiA-independent mechanism. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.13.571505. [PMID: 38168291 PMCID: PMC10760086 DOI: 10.1101/2023.12.13.571505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Through its cell cycle, the bacterium Caulobacter crescentus switches from a motile, free-living state, to a sessile surface-attached cell. During this coordinated process, cells undergo irreversible morphological changes, such as shedding of their polar flagellum and synthesis of an adhesive holdfast at the same pole. In this work, we used genetic screens to identify genes involved in the regulation of the motile to sessile lifestyle transition. We identified a predicted hybrid histidine kinase that inhibits biofilm formation and activates the motile lifestyle: HmrA (Holdfast and motility regulator A). Genetic screens and genomic localization led to the identification of additional genes that regulate the proportion of cells harboring an active flagellum or a holdfast and that form a putative phosphorelay pathway with HmrA. Further genetic analysis indicates that the Hmr pathway is independent of the holdfast synthesis regulator HfiA and may impact c-di-GMP synthesis through the diguanylate cyclase DgcB pathway. Finally, we provide evidence that the Hmr pathway is involved in the regulation of sessile-to-motile lifestyle as a function of environmental stresses, namely excess copper and non-optimal temperatures.
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Affiliation(s)
- Sébastien Zappa
- Département de microbiologie, infectiologie et immunologie, Université de Montréal, Montréal, Québec, CANADA
| | - Cecile Berne
- Département de microbiologie, infectiologie et immunologie, Université de Montréal, Montréal, Québec, CANADA
| | - Robert I. Morton
- Department of Biology, Indiana University, Bloomington, IN, USA
- Present address: Boston Scientific, Yokneam, Northern, ISRAEL
| | - Jonathan De Stercke
- Département de microbiologie, infectiologie et immunologie, Université de Montréal, Montréal, Québec, CANADA
- Present address: Unité de Recherche en Biologie des Micro-organismes, Université de Namur, 61 rue de Bruxelles, B-5000 Namur, BELGIUM
| | - Yves V. Brun
- Département de microbiologie, infectiologie et immunologie, Université de Montréal, Montréal, Québec, CANADA
- Department of Biology, Indiana University, Bloomington, IN, USA
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10
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Affiliation(s)
- Cecile Berne
- Département de microbiologie, infectiologie et immunologie, Université de Montréal, Montréal, Québec, Canada
- * E-mail:
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11
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Barrows JM, Goley ED. Synchronized Swarmers and Sticky Stalks: Caulobacter crescentus as a Model for Bacterial Cell Biology. J Bacteriol 2023; 205:e0038422. [PMID: 36715542 PMCID: PMC9945503 DOI: 10.1128/jb.00384-22] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
First isolated and classified in the 1960s, Caulobacter crescentus has been instrumental in the study of bacterial cell biology and differentiation. C. crescentus is a Gram-negative alphaproteobacterium that exhibits a dimorphic life cycle composed of two distinct cell types: a motile swarmer cell and a nonmotile, division-competent stalked cell. Progression through the cell cycle is accentuated by tightly controlled biogenesis of appendages, morphological transitions, and distinct localization of developmental regulators. These features as well as the ability to synchronize populations of cells and follow their progression make C. crescentus an ideal model for answering questions relevant to how development and differentiation are achieved at the single-cell level. This review will explore the discovery and development of C. crescentus as a model organism before diving into several key features and discoveries that have made it such a powerful organism to study. Finally, we will summarize a few of the ongoing areas of research that are leveraging knowledge gained over the last century with C. crescentus to highlight its continuing role at the forefront of cell and developmental biology.
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Affiliation(s)
- Jordan M. Barrows
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Erin D. Goley
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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12
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Pseudomonas aeruginosa distinguishes surfaces by stiffness using retraction of type IV pili. Proc Natl Acad Sci U S A 2022; 119:e2119434119. [PMID: 35561220 PMCID: PMC9171759 DOI: 10.1073/pnas.2119434119] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
While many bacteria can sense the presence of a surface, the mechanical properties of different surfaces vary tremendously and can be as rigid as bone or as soft as mucus. We show that the pathogen Pseudomonas aeruginosa distinguishes surfaces by stiffness and transcriptionally tunes its virulence to surface rigidity. This connection between pathogenicity and mechanical properties of the infection site presents an interesting potential for clinical applications. The mechanism behind stiffness sensing relies on the retraction of external appendages called type IV pili that deform the surface. While this mechanism has interesting parallels to stiffness sensing in mammalian cells, our results suggest that stiffness sensing in much smaller bacterial cells relies on temporal sensing instead of spatial sensing strategies. The ability of eukaryotic cells to differentiate surface stiffness is fundamental for many processes like stem cell development. Bacteria were previously known to sense the presence of surfaces, but the extent to which they could differentiate stiffnesses remained unclear. Here we establish that the human pathogen Pseudomonas aeruginosa actively measures surface stiffness using type IV pili (TFP). Stiffness sensing is nonlinear, as induction of the virulence factor regulator is peaked with stiffness in a physiologically important range between 0.1 kPa (similar to mucus) and 1,000 kPa (similar to cartilage). Experiments on surfaces with distinct material properties establish that stiffness is the specific biophysical parameter important for this sensing. Traction force measurements reveal that the retraction of TFP is capable of deforming even stiff substrates. We show how slow diffusion of the pilin PilA in the inner membrane yields local concentration changes at the base of TFP during extension and retraction that change with substrate stiffness. We develop a quantitative biomechanical model that explains the transcriptional response to stiffness. A competition between PilA diffusion in the inner membrane and a loss/gain of monomers during TFP extension/retraction produces substrate stiffness-dependent dynamics of the local PilA concentration. We validated this model by manipulating the ATPase activity of the TFP motors to change TFP extension and retraction velocities and PilA concentration dynamics, altering the stiffness response in a predictable manner. Our results highlight stiffness sensing as a shared behavior across biological kingdoms, revealing generalizable principles of environmental sensing across small and large cells.
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13
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Chen H, Tian Y, Hu Z, Wang C, Xie P, Chen L, Yang F, Liang Y, Mu C, Wei C, Ting YP, Qiu G, Song Y. Bis-(3′-5′)-cyclic dimeric guanosine monophosphate (c-di-GMP) mediated membrane fouling in membrane bioreactor. J Memb Sci 2022. [DOI: 10.1016/j.memsci.2021.120224] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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14
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Huang M, Zhang JY, Zeng X, Zhang CC. c-di-GMP Homeostasis Is Critical for Heterocyst Development in Anabaena sp. PCC 7120. Front Microbiol 2021; 12:793336. [PMID: 34925302 PMCID: PMC8682488 DOI: 10.3389/fmicb.2021.793336] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 11/09/2021] [Indexed: 12/04/2022] Open
Abstract
c-di-GMP is a ubiquitous bacterial signal regulating various physiological process. Anabaena PCC 7120 (Anabaena) is a filamentous cyanobacterium able to form regularly-spaced heterocysts for nitrogen fixation, in response to combined-nitrogen deprivation in 24h. Anabaena possesses 16 genes encoding proteins for c-di-GMP metabolism, and their functions are poorly characterized, except all2874 (cdgS) whose deletion causes a decrease in heterocyst frequency 48h after nitrogen starvation. We demonstrated here that c-di-GMP levels increased significantly in Anabaena after combined-nitrogen starvation. By inactivating each of the 16 genes, we found that the deletion of all1175 (cdgSH) led to an increase of heterocyst frequency 24h after nitrogen stepdown. A double mutant ΔcdgSHΔcdgS had an additive effect over the single mutants in regulating heterocyst frequency, indicating that the two genes acted at different time points for heterocyst spacing. Biochemical and genetic data further showed that the functions of CdgSH and CdgS in the setup or maintenance of heterocyst frequency depended on their opposing effects on the intracellular levels of c-di-GMP. Finally, we demonstrated that heterocyst differentiation was completely inhibited when c-di-GMP levels became too high or too low. Together, these results indicate that the homeostasis of c-di-GMP level is important for heterocyst differentiation in Anabaena.
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Affiliation(s)
- Min Huang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China.,College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Ju-Yuan Zhang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Xiaoli Zeng
- State Key Laboratory of Freshwater Ecology and Biotechnology, Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Cheng-Cai Zhang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China.,College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, China.,Institut AMU-WUT, Aix-Marseille University and Wuhan University of Technology, Wuhan, China.,Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, China
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15
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Ellison CK, Whitfield GB, Brun YV. Type IV Pili: Dynamic Bacterial Nanomachines. FEMS Microbiol Rev 2021; 46:6425739. [PMID: 34788436 DOI: 10.1093/femsre/fuab053] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 11/08/2021] [Indexed: 01/19/2023] Open
Abstract
Bacteria and archaea rely on appendages called type IV pili (T4P) to participate in diverse behaviors including surface sensing, biofilm formation, virulence, protein secretion, and motility across surfaces. T4P are broadly distributed fibers that dynamically extend and retract, and this dynamic activity is essential for their function in broad processes. Despite the essentiality of dynamics in T4P function, little is known about the role of these dynamics and molecular mechanisms controlling them. Recent advances in microscopy have yielded insight into the role of T4P dynamics in their diverse functions and recent structural work has expanded what is known about the inner workings of the T4P motor. This review discusses recent progress in understanding the function, regulation, and mechanisms of T4P dynamics.
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Affiliation(s)
- Courtney K Ellison
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ, USA.,Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Gregory B Whitfield
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montréal, Québec, Canada
| | - Yves V Brun
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montréal, Québec, Canada
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16
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Abstract
Bacteria have developed a large array of motility mechanisms to exploit available resources and environments. These mechanisms can be broadly classified into swimming in aqueous media and movement over solid surfaces. Swimming motility involves either the rotation of rigid helical filaments through the external medium or gyration of the cell body in response to the rotation of internal filaments. On surfaces, bacteria swarm collectively in a thin layer of fluid powered by the rotation of rigid helical filaments, they twitch by assembling and disassembling type IV pili, they glide by driving adhesins along tracks fixed to the cell surface and, finally, non-motile cells slide over surfaces in response to outward forces due to colony growth. Recent technological advances, especially in cryo-electron microscopy, have greatly improved our knowledge of the molecular machinery that powers the various forms of bacterial motility. In this Review, we describe the current understanding of the physical and molecular mechanisms that allow bacteria to move around.
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17
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Wong GCL, Antani JD, Lele PP, Chen J, Nan B, Kühn MJ, Persat A, Bru JL, Høyland-Kroghsbo NM, Siryaporn A, Conrad JC, Carrara F, Yawata Y, Stocker R, Brun YV, Whitfield GB, Lee CK, de Anda J, Schmidt WC, Golestanian R, O’Toole GA, Floyd KA, Yildiz FH, Yang S, Jin F, Toyofuku M, Eberl L, Nomura N, Zacharoff LA, El-Naggar MY, Yalcin SE, Malvankar NS, Rojas-Andrade MD, Hochbaum AI, Yan J, Stone HA, Wingreen NS, Bassler BL, Wu Y, Xu H, Drescher K, Dunkel J. Roadmap on emerging concepts in the physical biology of bacterial biofilms: from surface sensing to community formation. Phys Biol 2021; 18:10.1088/1478-3975/abdc0e. [PMID: 33462162 PMCID: PMC8506656 DOI: 10.1088/1478-3975/abdc0e] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 01/14/2021] [Indexed: 11/29/2022]
Abstract
Bacterial biofilms are communities of bacteria that exist as aggregates that can adhere to surfaces or be free-standing. This complex, social mode of cellular organization is fundamental to the physiology of microbes and often exhibits surprising behavior. Bacterial biofilms are more than the sum of their parts: single-cell behavior has a complex relation to collective community behavior, in a manner perhaps cognate to the complex relation between atomic physics and condensed matter physics. Biofilm microbiology is a relatively young field by biology standards, but it has already attracted intense attention from physicists. Sometimes, this attention takes the form of seeing biofilms as inspiration for new physics. In this roadmap, we highlight the work of those who have taken the opposite strategy: we highlight the work of physicists and physical scientists who use physics to engage fundamental concepts in bacterial biofilm microbiology, including adhesion, sensing, motility, signaling, memory, energy flow, community formation and cooperativity. These contributions are juxtaposed with microbiologists who have made recent important discoveries on bacterial biofilms using state-of-the-art physical methods. The contributions to this roadmap exemplify how well physics and biology can be combined to achieve a new synthesis, rather than just a division of labor.
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Affiliation(s)
- Gerard C L Wong
- Department of Bioengineering, University of California—Los Angeles, Los Angeles, California, CA 90095, United States of America
- Department of Chemistry and Biochemistry, University of California—Los Angeles, Los Angeles, California, CA 90095, United States of America
- California NanoSystems Institute, University of California—Los Angeles, Los Angeles, California, CA 90095, United States of America
| | - Jyot D Antani
- Artie McFerrin Department of Chemical Engineering, Texas A & M University, College Station, TX 77843, United States of America
| | - Pushkar P Lele
- Artie McFerrin Department of Chemical Engineering, Texas A & M University, College Station, TX 77843, United States of America
| | - Jing Chen
- Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA24061, United States of America
| | - Beiyan Nan
- Department of Biology, Texas A & M University, College Station, Texas, TX 77845, United States of America
| | - Marco J Kühn
- Institute of Bioengineering and Global Health Institute, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Alexandre Persat
- Institute of Bioengineering and Global Health Institute, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Jean-Louis Bru
- Department of Molecular Biology & Biochemistry, University of California—Irvine, California, CA 92697, United States of America
| | | | - Albert Siryaporn
- Department of Molecular Biology & Biochemistry, University of California—Irvine, California, CA 92697, United States of America
- Department of Physics & Astronomy, University of California—Irvine, California, CA 92697, United States of America
| | - Jacinta C Conrad
- William A Brookshire Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas, TX 77204, United States of America
| | - Francesco Carrara
- Institute of Environmental Engineering, Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, 8093 Zurich, Switzerland
| | - Yutaka Yawata
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan
- Microbiology Research Center for Sustainability, University of Tsukuba, 305-8572 Tsukuba, Japan
| | - Roman Stocker
- Institute of Environmental Engineering, Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, 8093 Zurich, Switzerland
| | - Yves V Brun
- University of Montreal, Faculty of Medicine, Montreal, Quebec, H3C 3J7, Canada
| | - Gregory B Whitfield
- University of Montreal, Faculty of Medicine, Montreal, Quebec, H3C 3J7, Canada
| | - Calvin K Lee
- Department of Bioengineering, University of California—Los Angeles, Los Angeles, California, CA 90095, United States of America
- Department of Chemistry and Biochemistry, University of California—Los Angeles, Los Angeles, California, CA 90095, United States of America
- California NanoSystems Institute, University of California—Los Angeles, Los Angeles, California, CA 90095, United States of America
| | - Jaime de Anda
- Department of Bioengineering, University of California—Los Angeles, Los Angeles, California, CA 90095, United States of America
- Department of Chemistry and Biochemistry, University of California—Los Angeles, Los Angeles, California, CA 90095, United States of America
- California NanoSystems Institute, University of California—Los Angeles, Los Angeles, California, CA 90095, United States of America
| | - William C Schmidt
- Department of Bioengineering, University of California—Los Angeles, Los Angeles, California, CA 90095, United States of America
- Department of Chemistry and Biochemistry, University of California—Los Angeles, Los Angeles, California, CA 90095, United States of America
- California NanoSystems Institute, University of California—Los Angeles, Los Angeles, California, CA 90095, United States of America
| | - Ramin Golestanian
- Max Planck Institute for Dynamics and Self-Organization (MPIDS), D-37077 Göttingen, Germany
- Rudolf Peierls Centre for Theoretical Physics, University of Oxford, Oxford OX1 3PU, United Kingdom
| | - George A O’Toole
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, United States of America
| | - Kyle A Floyd
- Department of Microbiology and Environmental Toxicology, University of California—Santa Cruz, Santa Cruz, California, CA 95060, United States of America
| | - Fitnat H Yildiz
- Department of Microbiology and Environmental Toxicology, University of California—Santa Cruz, Santa Cruz, California, CA 95060, United States of America
| | - Shuai Yang
- CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, People’s Republic of China
| | - Fan Jin
- CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, People’s Republic of China
| | - Masanori Toyofuku
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan
- Microbiology Research Center for Sustainability, University of Tsukuba, 305-8572 Tsukuba, Japan
| | - Leo Eberl
- Department of Plant and Microbial Biology, University of Zürich, 8008 Zürich, Switzerland
| | - Nobuhiko Nomura
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan
- Microbiology Research Center for Sustainability, University of Tsukuba, 305-8572 Tsukuba, Japan
| | - Lori A Zacharoff
- Department of Physics and Astronomy, University of Southern California, Los Angeles, California, CA 90089, United States of America
- Department of Chemistry, University of Southern California, Los Angeles, California, CA 90089, United States of America
| | - Mohamed Y El-Naggar
- Department of Physics and Astronomy, University of Southern California, Los Angeles, California, CA 90089, United States of America
- Department of Chemistry, University of Southern California, Los Angeles, California, CA 90089, United States of America
- Department of Biological Sciences, University of Southern California, Los Angeles, California, CA 90089, United States of America
| | - Sibel Ebru Yalcin
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, CT 06516, United States of America
- Microbial Sciences Institute, Yale University, New Haven, Connecticut, CT 06516, United States of America
| | - Nikhil S Malvankar
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, CT 06516, United States of America
- Microbial Sciences Institute, Yale University, New Haven, Connecticut, CT 06516, United States of America
| | - Mauricio D Rojas-Andrade
- Department of Materials Science and Engineering, University of California—Irvine, Irvine, California CA 92697, United States of America
| | - Allon I Hochbaum
- Department of Molecular Biology & Biochemistry, University of California—Irvine, California, CA 92697, United States of America
- Department of Materials Science and Engineering, University of California—Irvine, Irvine, California CA 92697, United States of America
- Department of Chemistry, University of California—Irvine, Irvine, California, CA 92697, United States of America
- Department of Chemical and Biomolecular Engineering, University of California—Irvine, Irvine, California, CA 92697, United States of America
| | - Jing Yan
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut, CT 06511, United States of America
| | - Howard A Stone
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey, NJ 08544, United States of America
| | - Ned S Wingreen
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, NJ 08544, United States of America
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, NJ 08544, United States of America
| | - Bonnie L Bassler
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, NJ 08544, United States of America
- The Howard Hughes Medical Institute, Chevy Chase, Maryland MD 20815, United States of America
| | - Yilin Wu
- Department of Physics and Shenzhen Research Institute, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, People’s Republic of China
| | - Haoran Xu
- Department of Physics and Shenzhen Research Institute, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, People’s Republic of China
| | - Knut Drescher
- Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
- Department of Physics, Philipps-Universität Marburg, 35043 Marburg, Germany
| | - Jörn Dunkel
- Department of Mathematics, Massachusetts Institute of Technology, Cambridge, Massachusetts, MA 02139-4307, United States of America
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18
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Acinetobacter baylyi regulates type IV pilus synthesis by employing two extension motors and a motor protein inhibitor. Nat Commun 2021; 12:3744. [PMID: 34145281 PMCID: PMC8213720 DOI: 10.1038/s41467-021-24124-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 06/02/2021] [Indexed: 11/08/2022] Open
Abstract
Bacteria use extracellular appendages called type IV pili (T4P) for diverse behaviors including DNA uptake, surface sensing, virulence, protein secretion, and twitching motility. Dynamic extension and retraction of T4P is essential for their function, and T4P extension is thought to occur through the action of a single, highly conserved motor, PilB. Here, we develop Acinetobacter baylyi as a model to study T4P by employing a recently developed pilus labeling method. By contrast to previous studies of other bacterial species, we find that T4P synthesis in A. baylyi is dependent not only on PilB but also on an additional, phylogenetically distinct motor, TfpB. Furthermore, we identify a protein (CpiA) that inhibits T4P extension by specifically binding and inhibiting PilB but not TfpB. These results expand our understanding of T4P regulation and highlight how inhibitors might be exploited to disrupt T4P synthesis. Type IV pili (T4P) are retractile appendages used by bacteria for DNA uptake and other purposes. T4P extension is thought to occur through the action of a single motor protein, PilB. Here, Ellison et al. show that T4P synthesis in Acinetobacter baylyi depends not only on PilB but also on an additional, distinct motor, TfpB.
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19
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Mignolet J, Mathelié-Guinlet M, Viljoen A, Dufrêne YF. AFM force-clamp spectroscopy captures the nanomechanics of the Tad pilus retraction. NANOSCALE HORIZONS 2021; 6:489-496. [PMID: 33982737 DOI: 10.1039/d1nh00158b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Motorization of bacterial pili is key to generate traction forces to achieve cellular function. The Tad (or Type IVc) pilus from Caulobacter crescentus is a widespread motorized nanomachine crucial for bacterial survival, evolution and virulence. An unusual bifunctional ATPase motor drives Tad pilus retraction, which helps the bacteria to land on target surfaces. Here, we use a novel platform combining a fluorescence-based screening of piliated bacteria and atomic force microscopy (AFM) force-clamp spectroscopy, to monitor over time (30 s) the nanomechanics and dynamics of the Tad nanofilament retraction under a high constant tension (300 pN). We observe striking transient variations of force and height originating from two phenomena: active pilus retraction and passive hydrophobic interactions between the pilus and the hydrophobic substrate. That the Tad pilus is able to retract under high tensile loading - at a velocity of ∼150 nm s-1 - indicates that this nanomachine is stronger than previously anticipated. Our findings show that pilus retraction and hydrophobic interactions work together to mediate bacterial cell landing and surface adhesion. The motorized pilus retraction actively triggers the cell to approach the substrate. At short distances, passive hydrophobic interactions accelerate the approach phenomenon and promote strong cell-substrate adhesion. This mechanism could provide a strategy to save ATP-based energy by the retraction ATPase. Our force-clamp AFM methodology offers promise to decipher the physics of bacterial nanomotors with high sensitivity and temporal resolution.
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Affiliation(s)
- Johann Mignolet
- Louvain Institute of Biomolecular Science and Technology, UCLouvain, Croix du Sud, 4-5, bte, L7.07.07, Louvain-la-Neuve B-1348, Belgium.
| | - Marion Mathelié-Guinlet
- Louvain Institute of Biomolecular Science and Technology, UCLouvain, Croix du Sud, 4-5, bte, L7.07.07, Louvain-la-Neuve B-1348, Belgium.
| | - Albertus Viljoen
- Louvain Institute of Biomolecular Science and Technology, UCLouvain, Croix du Sud, 4-5, bte, L7.07.07, Louvain-la-Neuve B-1348, Belgium.
| | - Yves F Dufrêne
- Louvain Institute of Biomolecular Science and Technology, UCLouvain, Croix du Sud, 4-5, bte, L7.07.07, Louvain-la-Neuve B-1348, Belgium.
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20
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Guzmán-Soto I, McTiernan C, Gonzalez-Gomez M, Ross A, Gupta K, Suuronen EJ, Mah TF, Griffith M, Alarcon EI. Mimicking biofilm formation and development: Recent progress in in vitro and in vivo biofilm models. iScience 2021; 24:102443. [PMID: 34013169 PMCID: PMC8113887 DOI: 10.1016/j.isci.2021.102443] [Citation(s) in RCA: 100] [Impact Index Per Article: 33.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Biofilm formation in living organisms is associated to tissue and implant infections, and it has also been linked to the contribution of antibiotic resistance. Thus, understanding biofilm development and being able to mimic such processes is vital for the successful development of antibiofilm treatments and therapies. Several decades of research have contributed to building the foundation for developing in vitro and in vivo biofilm models. However, no such thing as an "all fit" in vitro or in vivo biofilm models is currently available. In this review, in addition to presenting an updated overview of biofilm formation, we critically revise recent approaches for the improvement of in vitro and in vivo biofilm models.
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Affiliation(s)
- Irene Guzmán-Soto
- Division of Cardiac Surgery, University of Ottawa Heart Institute, Ottawa, ON, K1Y4W7, Canada
| | - Christopher McTiernan
- Division of Cardiac Surgery, University of Ottawa Heart Institute, Ottawa, ON, K1Y4W7, Canada
| | - Mayte Gonzalez-Gomez
- Division of Cardiac Surgery, University of Ottawa Heart Institute, Ottawa, ON, K1Y4W7, Canada
| | - Alex Ross
- Division of Cardiac Surgery, University of Ottawa Heart Institute, Ottawa, ON, K1Y4W7, Canada
- Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, ON, K1H8M5, Canada
| | - Keshav Gupta
- Division of Cardiac Surgery, University of Ottawa Heart Institute, Ottawa, ON, K1Y4W7, Canada
| | - Erik J. Suuronen
- Division of Cardiac Surgery, University of Ottawa Heart Institute, Ottawa, ON, K1Y4W7, Canada
| | - Thien-Fah Mah
- Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, ON, K1H8M5, Canada
| | - May Griffith
- Centre de Recherche Hôpital Maisonneuve-Rosemont, Montréal, QC, H1T 2M4, Canada
- Département d'ophtalmologie, Université de Montréal, Montréal, QC, H3T1J4, Canada
| | - Emilio I. Alarcon
- Division of Cardiac Surgery, University of Ottawa Heart Institute, Ottawa, ON, K1Y4W7, Canada
- Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, ON, K1H8M5, Canada
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21
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Nutrient complexity triggers transitions between solitary and colonial growth in bacterial populations. ISME JOURNAL 2021; 15:2614-2626. [PMID: 33731836 PMCID: PMC8397785 DOI: 10.1038/s41396-021-00953-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 02/18/2021] [Accepted: 02/25/2021] [Indexed: 12/31/2022]
Abstract
Microbial populations often experience fluctuations in nutrient complexity in their natural environment such as between high molecular weight polysaccharides and simple monosaccharides. However, it is unclear if cells can adopt growth behaviors that allow individuals to optimally respond to differences in nutrient complexity. Here, we directly control nutrient complexity and use quantitative single-cell analysis to study the growth dynamics of individuals within populations of the aquatic bacterium Caulobacter crescentus. We show that cells form clonal microcolonies when growing on the polysaccharide xylan, which is abundant in nature and degraded using extracellular cell-linked enzymes; and disperse to solitary growth modes when the corresponding monosaccharide xylose becomes available or nutrients are exhausted. We find that the cellular density required to achieve maximal growth rates is four-fold higher on xylan than on xylose, indicating that aggregating is advantageous on polysaccharides. When collectives on xylan are transitioned to xylose, cells start dispersing, indicating that colony formation is no longer beneficial and solitary behaviors might serve to reduce intercellular competition. Our study demonstrates that cells can dynamically tune their behaviors when nutrient complexity fluctuates, elucidates the quantitative advantages of distinct growth behaviors for individual cells and indicates why collective growth modes are prevalent in microbial populations.
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22
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An organelle-tethering mechanism couples flagellation to cell division in bacteria. Dev Cell 2021; 56:657-670.e4. [PMID: 33600766 DOI: 10.1016/j.devcel.2021.01.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 12/09/2020] [Accepted: 01/20/2021] [Indexed: 11/21/2022]
Abstract
In some free-living and pathogenic bacteria, problems in the synthesis and assembly of early flagellar components can cause cell-division defects. However, the mechanism that couples cell division with the flagellar biogenesis has remained elusive. Herein, we discover the regulator MadA that controls transcription of flagellar and cell-division genes in Caulobacter crescentus. We demonstrate that MadA, a small soluble protein, binds the type III export component FlhA to promote activation of FliX, which in turn is required to license the conserved σ54-dependent transcriptional activator FlbD. While in the absence of MadA, FliX and FlbD activation is crippled, bypass mutations in FlhA restore flagellar biogenesis and cell division. Furthermore, we demonstrate that MadA safeguards the divisome stoichiometry to license cell division. We propose that MadA has a sentinel-type function that senses an early flagellar biogenesis event and, through cell-division control, ensures that a flagellated offspring emerges.
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24
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Gheorghiu M. A short review on cell-based biosensing: challenges and breakthroughs in biomedical analysis. J Biomed Res 2020; 35:255-263. [PMID: 33888671 PMCID: PMC8383170 DOI: 10.7555/jbr.34.20200128] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 10/13/2020] [Accepted: 11/06/2020] [Indexed: 12/14/2022] Open
Abstract
Current cell-based biosensors have progressed substantially from mere alternatives to molecular bioreceptors into enabling tools for interfacing molecular machineries and gene circuits with microelectronics and for developing groundbreaking sensing and theragnostic platforms. The recent literature concerning whole-cell biosensors is reviewed with an emphasis on mammalian cells, and the challenges and breakthroughs brought along in biomedical analyses through novel biosensing concepts and the synthetic biology toolbox. These recent innovations allow development of cell-based biosensing platforms having tailored performances and capable to reach the levels of sensitivity, dynamic range, and stability suitable for high analytic/medical relevance. They also pave the way for the construction of flexible biosensing platforms with utility across biological research and clinical applications. The work is intended to stimulate interest in generation of cell-based biosensors and improve their acceptance and exploitation.
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Affiliation(s)
- Mihaela Gheorghiu
- Biosensors Department, International Centre of Biodynamics, Bucharest 060101, Romania
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